None and Optional handling

For more information, see the None and Optional handlingsection of the command line docs.

• no_implicit_optional (bool, default False)
• Changes the treatment of arguments with a default value of None by not implicitlymaking their type Optional.
• strict_optional (bool, default True)
• Enables or disables strict Optional checks. If False, mypy treats Noneas compatible with every type.

Note: This was False by default in mypy versions earlier than 0.600.